Table 2.

Characteristics of the included studies

Study	Design	Sample size and gender	Age in years Mean ± SD or range	COVID-19 severity, n	Oral signs and symptoms reported, n	Results
Marouf et al (2021)	Case control	n = 568 Control: n = 528 M = 290 (54.9%) F = 238 (45.1%) Case: n = 40 M = 20 (50%) F = 20 (50%)	Control = 41.5 ±14.1 Case = 53.6 ±15.0	Control: Covid positive patients without complications (n = 528) Case: Covid positive patients with complications (n = 40): Death = 14 ICU admission = 36 Need for assisted ventilation = 20	Periodontally healthy or initial periodontitis (stages 0-1): Bone loss < coronal third of the root length (15%) in OPGs, or ≤2 mm in bitewing radiographs. Control = 303 Case = 18 Periodontitis (stages 2-4): Bone loss > coronal third of the root length (>15%) in OPGs, or >2 mm in bitewing radiographs. Control = 225 Case = 92	Periodontitis associated with COVID-19 complications: Death (OR = 8.81, 95% CI 1.00-77.7) ICU admission (OR = 3.54, 95% CI 1.39-9.05) Need for assisted ventilation (OR = 4.57, 95% CI 1.19- 17.4)
Larvin et al (2020)	Case control	n = 13.253 Control: n = 9.815 M = 4789 (48.8%) F = 5026 (51.2%) Case: n = 1.338 M = 711 (53.1%) F = 627 (46.9%)	Control = 69.10±8.20 Case = 67.15 ±9.19	No self-reported history of periodontal disease: Control = covid negative patients = 9.815 Death = 292 (3.0%) Hospital admission = 2.723 (27.7%) Case = Covid positive patients = 1.338 Death = 247(18.5%) Hospital admission = 665 (49.7%)	Painful gums Control = 321 Case = 44 Bleeding gums Control = 1148 Case = 181 Loose teeth Control = 353 Case = 53	COVID-19 positive participants: Painful or bleeding gums had a higher risk of mortality (OR: 1.71, 95% CI: 1.05–2.72) but not hospital admission (OR: 0.90, 95% CI: 0.59–1.37). Loose teeth did not show higher risk of hospital admission or mortality compared to the control group (OR = 1.55, 95% CI: 0.87–2.77; OR: 1.85; 95% CI: 0.92–2.72)
Fernandes Matuck et al (2021)	Case series	n = 7 M = 3 (42.85%) F = 4 (57.14%)	47.4 (8-74)	Death = 7	Periodontal tissue positive for SARS-CoV-2 (RT-PCR) = 5 Periodontal tissue negative for SARS-CoV-2 (RT-PCR) = 2	Presence of SARS-CoV-2 in periodontal tissue in COVID-19 positive patients
Gupta et al (2021)	Cross-sectional study	n = 82 M = 48 (58.5%) F = 34 (41.46%)	Periodontally healthy = 34.44 ± 11.06 Gingivitis = 37.71 ± 10.0 Stage I periodontitis = 52.33 ± 16.25 Stage II periodontitis = 44.00 ± 18.38 Stage III periodontitis = 62.94 ± 12.76 Stage IV periodontitis = 61.58 ± 9.07	COVID-19 positive patients confirmed by nasopharyngeal swab (NPS) testing = 82 - COVID-19 symptoms: Symptomatic = 51 Asymptomatic = 31 - Hospital admission = 53 - Oxygen requirement = 30 - COVID-19 pneumonia = 22 - Deceased = 8	Periodontally healthy = 27 Gingivitis = 21 Stage I periodontitis = 3 Stage II periodontitis = 2 Stage III periodontitis = 17 Stage IV periodontitis = 12	Higher severity of periodontitis led to 7.45 odds of requiring assisted ventilation, 36.52 odds of hospital admission, 14.58 odds of being deceased and 4.42 odds of COVID-19-related pneumonia
Anand et al (2021)	Case control	n = 150 Control = 71 M = 35 F = 36 Case = 79 M = 50 F = 29	Control = 38.24 ± 10.72 Case = 43.34 ± 10.16	Control: Covid negative patients (n = 71) Case: Covid positive patients after rRT-PCR (n = 79)	Plaque score ≥ 1: - Control: 3 (4.2%) - Case: 19 (24.1%) Gingivitis: - Control: 36 (50.7%) - Case: 74 (93.7%) Mean CAL ≥ 2: - Control: 15 (21.1%) - Case: 51 (64.6%) Severe periodontitis - Control: 7 (9.9%) - Case: 39 (49.4%)	Periodontitis associated with COVID-19. Mean plaque scores ≥ 1 (OR, 7.01; 95% CI, 1.83-26.94) Gingivitis (OR, 17.65; 95% CI, 5.95-52.37) Mean CAL ≥ 2 mm (OR, 8.46; 95% CI, 3.47-20.63) Severe periodontitis (OR, 11.75; 95% CI, 3.89- 35.49)
Iwasaki et al (2021)	Cross-sectional questionnaire regarding the status of regular dental visits during the COVID-19 pandemic	n = 199 M = 123 (61.8%) F = 76 (38.2%)	42.6 ± 10.4	NR Japanese office workers during the COVID-19 pandemic	Group that continued regular visits (n = 77): - Periodontitis = 38 (49.4%) - Severe periodontitis = 4 (5.2%) Group that discontinued regular dental visits (n = 31) - Periodontitis = 24 (77.4%) - Severe periodontitis = 1 (3.2%) Group that did not attend regular dental visits (n = 91) - Periodontitis = 56 (61.5%) - Severe periodontitis = 10 (11.0%)	Individuals who discontinued regular dental visits had a higher prevalence of periodontitis (49.4% vs 77.4%, p < 0.05) and concerns regarding dental visits (22.1% vs 64.5%, p < 0.05). Discontinuing regular dental visits significantly mediated the association between concerns regarding dental visits and periodontitis (natural indirect effect: odds ratio = 1.68, 95% confidence interval = 1.02–2.79, proportion mediated = 64.3%)
Fantozzi et al (2020)	Retrospective cohort study Modified survey from (NHANES) 2013–2014 for taste and smell disorders and the Fox Questionnaire for dry mouth	n = 111 M = 58 (52.3%) F = 53 (47.7%)	57 (48-67)	SARS-CoV-2 positive patients with real-time polymerase chain reaction (RT-PCR) = 111	Xerostomia = 51 (45.9%) Dysgeusia = 66 (59.5%)	Xerostomia, gustatory and olfactory dysfunctions may present as a prodromal or as the sole manifestation of COVID-19
Freni et al (2020)	Cross-sectional study Questionnaire of Olfactory Disorders-Negative Statements (sQOD-NS) The Summated Xerostomia Inventory-Dutch Version (SXI-DV) The Standardised Patient Evaluation of Eye Dryness (SPEED) Schirmer test I The Hearing Handicap Inventory For Adults (HHIA) Tinnitus Handicap Inventory (THI)	n = 50 M = 30 (60%) F = 20 (40%)	37.7 ± 17.9	Laboratory-confirmed COVID-19 infection with real-time polymerase chain reaction (RT-PCR) = 50	During convalescence (Condition A): Gustatory dysfunction = 35 Xerostomia = 16 After 15 days from RT-PCR SARS-COV-2 negativity (Condition B): Gustatory dysfunction = 4 Xerostomia = 1	During convalescence (Condition A): OR (95% CI) - Gustatory dysfunction = 26.81 (8.1–87.9) - Xerostomia = 23.05 (2.9-182.2)
Biadsee et al (2020)	Case series Questionnaire	n = 128 M = 58 F = 70	36.25 (18-73)	SARS-CoV-2 positive patients with real-time polymerase chain reaction (RT-PCR), ambulatory, nonhospitalised patients	Taste disorders = 67 Dry mouth = 72 Facial pain = 18 (women) Masticatory muscle pain = 15 Additional oral manifestations: - Plaque-like changes in the tongue = 9 - Swelling = 10 - Oral bleeding = 6	A considerable number of patients presented with olfactory and oral disorders. Impaired sense of taste was observed in 52% of the patients and xerostomia in 56%. Anosmia and facial pain were more common among women (p < 0.001 and p = 0.01, respectively)
Politi et al (2020)	Retrospective analysis	n = 111 (total number of patients seen by the Oral and maxillofacial surgery specialists during the initial six weeks of COVID-19 lockdown in 2020) M = 64% F = 36%	42 (6-72)	NR: Patients with cervicofacial infection of dental etiology referred to maxillofacial surgery during the initial six weeks of COVID-19 lockdown in 2020 compared with the equivalent period in the two preceding years = 22	Cervicofacial infection during COVID-19 lockdown in 2020 = 22 - Patients requiring hospital admission = 10 (45%) - Post extraction infections = 0 (0%) - Total patients receiving antibiotics = 22 (100%) - Oral = 7 (32%) - IV Single dose + Oral = 5 (23%) - IV Inpatient = 10 (45%) - Patients having antibiotic therapy prior to presentation to OMFS = 12 (55%) - Admitted patients undergoing incision and drainage (extraoral / intraoral) = 10 (100%) - General anaesthesia = 8 (80%) - Local anaesthesia = 2 (20%) - Extraoral drainage = 5 (50%) - Intraoral drainage = 5 (50%) - Not admitted patients = 12 (55%) - Incision and drainage under local anaesthesia = 7 (58%) - No treatment = 5 (42%)	During COVID-19 lockdown in 2020: - Overall decrease in the number of cases seen with cervicofacial infection of dental origin - A high percentage of those seen required hospital admission - They required more invasive treatment with an increase in intraoral drainage under LA and extraoral drainage under GA - There was a decrease in the length of in-patient stay
Wu et al (2021)	Retrospective analysis	n = 4158 Pre-SARS-COV-2 = 1716 M = 873 (50.9%) F = 843 (49.1%) SARS-COV-2 = 2442 M = 1236 (50.6%) F = 1206 (49.4%)	Pre-SARS-COV-2 = 24.7 ± 16.7 SARS-COV-2 = 33.0 ± 19.4	NR: Dental emergency patients in the SARS-COV-2 period (January 20 to March 8, 2020), compared with the number of patients admitted to the emergency center before the SARS-COV-2 pandemic (January 21 to March 10, 2019)	Acute pulpitis and/or acute apical periodontitis: - Pre-SARS-COV-2 = 413 (25.9%) - SARS-COV-2 = 858 (35.1%) Acute gingivitis and/or acute pericoronitis: - Pre-SARS-COV-2 = 314 (18.2%) - SARS-COV-2 = 529 (21.7%) Temporomandibular joint disorders: - Pre-SARS-COV-2 = 24 (1.4%) - SARS-COV-2 = 56 (2.3%) Cellulitis and abscess of the oral cavity: - Pre -SARS-COV-2 = 161 (9.6%) - SARS-COV-2 = 227 (9.3%) Open wound of the lip and oral cavity: - Pre -SARS-COV-2 = 695 (38.0%) - SARS-COV-2 = 492 (20.1%) Fracture of tooth: - Pre-SARS-COV-2 = 58 (3.2%) - SARS-COV-2 = 23 (0.9%) Others (prosthesis, aesthetic, recall, or maintenance): - Pre-SARS-COV-2 = 51 (3.7%) - SARS-COV-2 = 257 (10.5%)	During the SARS-COV-2 pandemic, the number of dental emergency visits increased by 29.7%. Trauma, acute pulpitis, and acute periodontitis were the leading causes of patients visiting the dental emergency
Ramírez et al (2021)	Observational study	n = 261 M = 128 F = 133	20 months to 87 years	NR: Odontostomatological emergencies (OSE) treated between March 17th and 4th of May 2020 in four dental clinics in Madrid (Spain)	Acute apical periodontitis = 143 (54.7%) Acute irreversible pulpitis = 32 (12.2%) Dental fracture = 25 (9.5%) Pericoronaritis = 17 (6.5%) Odontogenic abscess = 15 (2.3%) Prosthetics = 29 (11.1%)	The most prevalent pathology was acute apical periodontitis, whereas odontogenic abscess showed the lowest frequency. Prosthetic-orthodontic OSE represented 14% of cases
Sirin et al. (2021)	Retrospective analysis	n = 137 M = 71 (52%) F = 66 (48%)	20–65	Positive real time PCR COVID-19 test	Dental damage stage 0 = 31 Chronic disease = 1 (3%) Number of dental caries = 0.2 ± 0.4 Number of missing teeth = 3.9 ± 3.2 Number of hospitalisations due to COVID-19 = 0 (0%) Symptom associated with COVID-19 = 11 (35%) - Dental damage stage 1 = 30 Chronic disease = 3 (10%) Number of dental caries = 1.0 ± 1.2 Number of missing teeth = 5.2 ± 5.7 Number of hospitalisations due to COVID-19 = 3 (10%) Symptom associated with COVID-19 = 25 (83%) Dental damage stage 2 = 44 Chronic disease = 20 (45%) Number of dental caries = 1.9 ± 1.5 Number of missing teeth = 6.4 ± 5.6 Number of hospitalisations due to COVID-19 = 13 (30%) Symptom associated with COVID-19 = 39 (89%) Dental damage stage 3 = 32 Chronic cisease = 17 (53%) Number of dental caries = 2.5 ± 2.0 Number of missing teeth = 10.0 ± 6.5 Number of hospitalisations due to COVID-19 = 24 (75%) Symptom associated with COVID-19 = 31 (97%)	Dental damage stage: - Positive high correlation with number dental caries (NDC) - Positive moderate correlation with number of hospitalisations due to COVID-19 (NHC) and Symptom associated with COVID-19 (SAC) - Positive moderate correlation with presence of chronic disease (CD) - Dental damage stage 3 : Significantly higher age and mortality - Chronic disease (CD), numbers of dental caries (NDC) and hospitalisation due to COVID-19 (NHC) values were higher in dental damage stage 2 and 3 than in dental damage stage 0 and 1. - Hospitalisation due to COVID-19 (NHC) were higher in dental damage stage 3 than in dental damage stage 2 - Missing teeth (NMT) were higher in dental damage stage 3 than other stages. - Symptom associated with COVID-19 (SAC) were significantly lower in dental damage stage 0 than in dental damage stage 1, 2 and 3 - Numbers of dental caries (NDC), hospitalisation due to COVID-19 (NHC), Symptom associated with COVID-19 (SAC) and Chronic disease (CD) were effective on DD staging; they were moderately positively related.
Kamel et al (2021)	Cross-sectional questionnaire survey	n = 308 M = 104 (33.8%) F = 204 (66.2%)	34.98 ± 8.08	SARS-CoV-2 confirmed by (RT-PCR) Severe COVID-19 description: - High respiratory rate (>30 breaths/min) - Heart rate >100 beats/min - Severe dyspnoea or chest pain - Oxygen saturation <93% - High-grade fever (>39 °C) - Hospitalised patients who required oxygen or intensive care unit admission	Poor oral health: - Severe COVID-19 = 52 (65%) - Mild COVID-19 = 12 (5.3%) 6 weeks recovery period n = 26 (40.6%) 4 weeks recovery period n = 28 (43.8%) 2 weeks recovery period n = 10 (15.6%) Fair oral health: - Severe COVID-19 = 20 (25%) - Mild COVID-19 = 146 (64%) 6 weeks recovery period n = 18 (10.8%) 4 weeks recovery period n = 54 (32.5%) 2 weeks recovery period n = 94 (56.6%) Good oral health: - Severe COVID-19 = 8 (10%) - Mild COVID-19 = 70 (30.7%) 6 weeks recovery period n = 6 (7.7%) 4 weeks recovery period n = 8 (10.3%) 2 weeks recovery period n = 64 (82.1%)	Oral health and COVID-19 severity showed a significant inverse correlation (p<0.001, r = -0.512) Oral health with recovery period and CRP values showed significant inverse correlation (p<0.001, -0.449 and p<0.001, -0.190, respectively)
Salehi et al (2020)	Cross-sectional study	n = 53 M = 23 (43.4%) F = 30 (56.6%)	<50 = 11 (20.7%) ≥50 = 42 (79.3%)	SARS-CoV-2 positive patients	Oropharyngeal candidiasis (OPC) = 53 Time interval between diagnosis of COVID-19 and clinical presentations of OPC = 8 days (range: 1-30 days) - Principal underlying conditions: CV diseases = 28 (52.8%) Diabetes = 20 (37.7%) - The most common risk factor: Lymphopaenia = 38 (71.7%) Recipient broad-spectrum antibiotics = 49 (92%) Corticosteroid therapy = 25 (47%) Admission to ICU = 26 (49%) Mechanical ventilation = 16 (30%) - Distribution of Candida species: 65 Candida isolates causing OPC C. albicans (70.7%) C. glabrata (10.7%) C. dubliniensis (9.2%) C. parapsilosis sensu stricto (4.6%) C. tropicalis (3%) C. krusei (1.5%)	Concerns regarding the occurrence of OPC in Iranian COVID-19 patients
Hocková et al (2021)	Case series	n = 9 Gender NR for all the patients, only for oral complications patients: M = 3 F = 0	NR for all the patients, only for oral complications patients: N 1 = 68 N 2 = 61 N 3 = 64	SARS-CoV-2 positive critically ill patients (RT-PCR) admitted to the intensive care units (ICUs)	Oral complications = 3 (33. 3%) - Haemorrhagic ulcers and necrotic ulcers affecting the lips and tongue - Presence of opportunistic pathogens, confirming the possibility of co-infection	Three out of nine critically ill patients (33.3%) presented with oral complications including haemorrhagic ulcers and necrotic ulcers affecting the lips and tongue
Sinjari et al (2020)	Observational study Questionnaire of 32 questions	n = 20 M = 55% F = 45%	69.2 (35-91)	Hospitalised patients for COVID-19	Oral manifestation of the hospitalised patients for COVID-19: - Xerostomia, none of the patients reported xerostomia before contracting the virus, whilst during hospitalisation the percentage increased to 30% (p = 0.02) - Impaired taste = 25% of patients during hospitalisation - Burning sensation = 15% of patients during hospitalisation - Difficulty in swallowing = 20% of patients during hospitalisation	Importance of the close link between SARS-CoV-2 and oral manifestations. There is no scientific evidence in the literature that certifies which oral symptoms SARS-CoV-2 can cause
Favia et al (2021)	Case-Series	n = 123 M = 70 F = 53	Form of Covid-19 - Moderate: 63 - Severe: 74 - Critical: 81	SARS-CoV-2 (confirmed by RT-PCR) hospitalised patients	Form of COVID-19: Moderate: n = 95 (77%) Type of oral lesions: - Geographic tongue = 5 - Fissured tongue = 4 - Ulcerative lesion = 51 - Blisters = 14 - Hyperplasia of papillae = 33 - Angina bullosa = 8 - Candidiasis = 18 - Ulcero-necrotic gingivitis = 1 - Petechiae = 4 Oral Symptoms: - Pain - Burning - Bleeding - Difficulty to chewing and swallow - Taste disorders = 87% Severe: n = 21 (17%) Type of oral lesions: - Geographic tongue = 2 - Fissured tongue = 1 - Ulcerative lesion = 11 - Blisters = 5 - Hyperplasia of papillae = 13 - Angina bullosa = 2 - Candidiasis = 4 - Ulcero-necrotic gingivitis = 2 - Petechiae = 6 Oral symptoms: - Pain - Burning - Bleeding - Difficulty to chewing and swallow - Taste disorders = 88% Critical: n = 8 (6%) Type of oral lesions: - Ulcerative lesion = 3 - Hyperplasia of papillae = 2 - Angina bullosa = 1 - Candidiasis = 6 - Ulcero-necrotic gingivitis = 4 - Petechiae = 4 - Spontaneous oral hemorrhage = 1 Oral symptoms: - Pain - Burning - Bleeding - Difficulty to chewing and swallow - Taste disorders = 83%	Oral lesions in 65.9% occurred in the early stage of Covid-19 before the beginning of specific therapies. Moreover, this study discovered that the physio-pathological mechanism underlying the formation of early oral lesions is the thrombosis of sub-epithelial and deeper vessels. The presence of oral lesions in early stages of Covid-19 could represent an initial sign of peripheral thrombosis, a warning sign of possible development to severe illness. This suggests that anticoagulant therapies should start as soon as possible
Huang et al (2021)	Prospective cohort study	9 samples of human minor salivary glands and gingiva (13,824 cells) NR	NR	SARS-CoV-2 positive patients	They confirmed SARS-CoV-2 infection in the glands and mucosae. Saliva from SARS-CoV-2-infected individuals harbored epithelial cells exhibiting ACE2 and TMPRSS expression and sustained SARS-CoV-2 infection	Acellular and cellular salivary fractions from asymptomatic individuals were found to transmit SARS-CoV-2 ex vivo. Matched nasopharyngeal and saliva samples displayed distinct viral shedding dynamics, and salivary viral burden correlated with COVID-19 symptoms, including taste loss. Upon recovery, this asymptomatic cohort exhibited sustained salivary IgG antibodies against SARS-CoV-2
Jimenez-Cauhe et al (2020)	Case-Series	n = 21 Gender NR for all the patients, only for Enanthem patients (6 patients) M = 2 (34%) F = 4 (66%)	NR for all the patients, only for Enanthem patients (6 patients) 40 - 69 years	SARS-CoV-2 positive patients	Enanthems located in palate = 6 Petechial = 2 Macular with petechiae = 3 Macular = 1	Presence of enanthem is a strong clue that suggests a viral etiology rather than a drug reaction, especially when a petechial pattern is observed
Nuño González et al (2021)	Cross-sectional study	n = 666 NR	NR	Hospitalised patients with coronavirus disease 2019 pneumonia	Oral mucosal changes = 78 (11,7%) - Transient U-shaped lingual papillitis = 35 (11.5%) - Tongue swelling = 20 (6.6%) - Glossitis with patchy depapillation = 12 (3.9%) - Mucositis = 12 (3.9%) - Aphthous ulcers = 21 (6.9%) - Burning mouth = 16 (5.3%) - White tongue = 5 (1.6%) - Candidiasis = 3 (1%) - Enanthema = 2 (0.5%)	COVID-19 also manifests in the oral cavity. The most common manifestations are transient U-shaped lingual papillitis, glossitis with patchy depapillation, and burning mouth syndrome
Fidan et al (2021)	Prospective study	n = 74 M = 49 (66.2%) F = 25 (33.8%)	51.4 ± 6.3	SARS-CoV-2 confirmed by (RT-PCR) patients	Oral lesions and distribution oral lesion areas = 58 - Aphthous-like ulcer = 27 - Erythema = 19 - Lichen planus = 12 The most common location of lesions - Tongue = 23 - Buccal mucosa = 20 - Gingiva = 11 - Palate = 4	Oral lesions in fifty-eight of seventy-four Covid 19 patients. There are limited reports about oral lesions in patients with Covid 19
AbuBakr et al (2021)	Cross-sectional online questionnaire survey	n = 573 M = 165 F = 408	36.19 ±9.11 (19–50)	SARS-CoV-2 confirmed by (RT-PCR): – Mild-to-moderate symptoms, without severe respiratory failure, not hospitalised	Occurrence of oral manifestations = 411 (71.7%) Pain in jaw bones or joint = 69 (12%) Halitosis = 60 (10.5%) Ulcerations = 117 (20.4%) Xerostomia = 273 (47.6%) Oral or dental pain = 132 (23%) Combined manifestations = 162 (28.3%)	Mild-to-moderate cases of COVID-19 infection are associated with oral symptoms. Statistically significant difference in the incidence of oral manifestations in relation to the oral hygiene measures taken by the patients
Subramaniam et al (2021)	Observational study	n = 713 M = 416 F = 297	NR for all the patients, only for patients with oral lesions (9 patients) 43-70 years	SARS-CoV-2 confirmed by (RT-PCR)	Differential diagnosis: - Patient 1 = Traumatic ulcer secondary to cheek bite - Patient 2 = Diabetic mucositis - Patient 3 = Geographic tongue (related to psychosomatic disorders) and traumatic ulcers - Patient 4 = Acute/chronic pseudomembranous candidiasis (thrush) - Patient 5 = Geographic tongue and nutritional deficiency mucositis - Patient 6 = recurrent herpetic labialis. Nutritional deficiency angular cheilitis - Patient 7 = traumatic ulcer with bloody encrustations (history of intubation) - Patient 8 = ulceration secondary to nutritional deficiency/benign migratory glossitis - Patient 9 = mucositis secondary to anemia and xerostomia	Among 713 patients positive to coronavirus, who were screened for oral lesions, only nine patients had complaints. No specific pattern or characteristic oral lesions were noted in a study of 713 COVID-positive patients to qualify these lesions as oral manifestations of SARS-CoV-2 infection
Emodi-Perlman et al (2020)	Cross-sectional online survey (regarding TMD, bruxism, anxiety and depression: 3Q/TMD, possible/probable bruxism, and Patient Health Questionnaie-4, as detailed below)	n = 1792 From Israel = 700 M = 235 (33.6%) F = 465 (66.4%) From Poland = 1092 M = 454 (41.6%) F = 638 (58.4%)	From Israel = 700 18–35 = 203 36–55 = 283 >56 = 200 N/A = 14 From Poland = 1092 18–35 = 828 36–55 = 234 > 56 = 30 N/A = 0	NR Subjects selected from two culturally different countries during the lockdown: Israel and Poland	TMD Positive: - Israel = 152 - Poland = 576 TMD Negative: - Israel = 548 - Poland = 516 Awake bruxism (AB): - Israel: Probable AB (I) = 153 Possible AB (II) = 125 AB Negative (III) = 422 - Poland: Probable AB (I) = 378 Possible AB (II) = 365 AB Negative (III) = 349 Sleep bruxism (SB): - Israel: Probable SB (I) = 152 Possible SB (II) = 70 SB Negative (III) = 478 - Poland: Probable SB (I) = 351 Possible SB (II) = 199 SB Negative (III) = 542	TMD: Odds of occurrence of TMDs among the Polish young adult and adult age groups (18–35 years and 36–55 years) were significantly higher for both males and females as compared to the Israeli groups (odds ratios ranged from 3.04 to 5.37). Awake bruxism (AB): Odds of occurrence among the Polish participants were significantly higher in general than among the Israeli participants (except the young and elder males), with the odds ratios ranging between 2.51 and 6.41. Sleep bruxism (SB): Odds of occurrence among the Polish subjects (except for males in the two higher age groups) were similar to those of the Israeli subjects, with the odds ratios ranging from 1.4 to 3.99
Asquini et al (2021)	Prospective cohort study	n = 40 Chronic TMD = 16 - M = 6% - F = 94% Acute/sub- acute TMD = 24 - M = 12% - F = 88%	Chronic TMD = 28 (median) Acute/sub- acute TMD = 29 (median)	NR Patients with one or multiple TMD diagnoses before the Covid-19 outbreak and followed-up performed immediately after the lockdown period	Chronic TMD = 16 Acute/sub-acute TMD = 24	COVID Stress Scales (CSS) were significantly higher in those with chronic TMDs compared to those with acute/subacute TMDs (p<0.05)
Petrescu et al (2020)	Retrospective Cross-sectional study	April 2020 n = 724 M = 53.59% F = 46.41%	April 2020 = 2-96	NR Patients seeking emergency dental services at the Emergency Department of County General Hospital and “Iuliu Hat, ieganu” University of Medicine and Pharmacy, Cluj-Napoca, Romania, in April 2020	Disease type and diagnosis: April 2020 = 724 Acute pulpitis = 244 Acute apical periodontitis = 324 Pericoronitis of the impacted teeth = 11 Post-extractional alveolitis = 1 Abscess = 73 Dislocation temporo-mandibular joint = 1 Dento-alveolar trauma = 40 Ulcer-necrotic gingivitis = 6 Orthodontic appliance irritation injury = 7 Prosthetic crown loosening = 12 Pathological dental mobility = 12 Other injury (irritative, ulcerative, decubitus) = 43 Caries = 13	Treatment of oral emergencies: April 2020: Sedative filling = 191 (29.28%) Drainage (endodontic) = 92 (14.09%) Drainage/antiseptic lavage = 75 (11.46%) Drainage/sedative filling = 6 (0.97%) Extraction = 14 (2.07%) Incision/drainage = 8 (1.24%) Incision/drainage/antiseptic lavage = 3 (0.55%) Antiseptic lavage = 12 (1.8%) Pulpectomy = 11 (1.66%) Suppression of irritant factor = 12 (1.8%) Filling = 0 (0%) Other = 31 (4.7%) Examination/consultation only = 198 (30.36%)
Zhang et al (2021)	Nationwide online cross-sectional survey of 22 questions (24 January 2020 to 2 May 2020)	n = 3352 M = 1217 (36.31%) F = 2135 (63.69%)	18-30 = 1241 (37.02%) 31-50 = 1582 (47.19%) ≥51 = 529 (15.79%)	NR Participants from Wuhan and other places of China (24 January 2020 to 2 May 2020)	Oral problems: - Wuhan = 63.30% - Other places of China = 57.07% Global oral problems: - Gingival bleeding = 23% - Bad breath = 20% - Oral ulcers = 17% - Other problems = 14% - Swelling = 12% - Toothache = 9% - TMJ disorders = 5%	Significantly more participants in Wuhan (63.30%) experienced oral problems than other places in China (57.07%). Gingival bleeding, bad breath and oral ulcers were the three most common oral problems amid the epidemic. Toothbrushing frequency did not differ significantly between participants from Wuhan and other places and was associated with the prevalence of oral problems